Expansion joints found, for example, in the external walls of high rise structures or between concrete slabs of a road surface are vital to allow the release of stress due to thermal expansion or contraction. Obviously, such a joint in buildings must be sealed to exclude weather, but in addition, it is vital that the joint be sealed to prevent the collection of foreign matter or debris therein. Accumulation of foreign matter or debris in an expansion joint will result in a loss of function in the joint due to an inability to close. This is clearly a danger with road joints or joints in other horizontal surfaces where foreign matter easily accumulates. It is also desirable to seal an expansion joint to prevent water from accumulating behind or beneath a surface with subsequent heaving when temperatures fall below freezing, and in the case of on grade concrete applications, to prevent the erosion of the supporting sub soil.
Expansion joint seals are commonly made either by pumping an asphalt or curable rubber compound into the joint or by inserting a sealing strip of rubber, plastic or other such material thereinto. It is no surprise, however, that these seals exposed to weather and possibly to the rigors of road traffic do not have the functional life of the concrete, stone or steel joints which they seal. Seals fail when adhesion to or contact with a face of the joint is lost by deterioration of the materials used in the seal or by excessive force applied. Various designs have been proposed to increase the functional life of the seal.
U.S. Pat. No. 4,615,151 teaches that metal anchors should be imbedded into wet concrete at the expansion joint rim that will upon setting be used to secure a flexible seal of the joint and prevent adhesive failure. U.S. Pat. No. 3,368,464 teaches that a flexible seal with premounted anchors should be imbedded into the concrete prior to setting. U.S. Pat. No. 3,286,425 teaches a flexible seal, which through compressive force against the opposing edges of the joint maintains its position in the joint. U.S. Pat. No. 2,315,588 shows another seal which utilizes simple compressive force. U.S. Pat. No. 3,923,411 shows a seal that uses a combination of compressive force with fluted members to prevent a seal from dislodging from the joint.
Each of the above mentioned seals have problems in connection with their use. Obviously, seals that must be inserted before concrete is set require that different methods of "forming" concrete be utilized. Such methods are not convenient and are not applicable to steel or granite, for instance. Seals that rely along on compressive force are easily inserted and replaced, but tend not to have a long functional life. The compression of these seals varies with expansion and contraction of the opposing joint faces adversely effecting the performance of the seal.
It is an object of the present invention to produce an expansion joint seal having a long functional life.
It is a further object of the present invention to produce such a seal that will remain firmly bonded and in contact with the faces of the expansion joint.
It is also an object of the invention to relieve the bonding faces of the seal of the tensile stress of contraction or compressive stress of expansion.
It is further object of the invention to produce a seal which is easily inserted and bonded into an expansion joint.